Self-adjusting feed mechanism



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G. EHRHARDT. SELF ADJUSTING FEED MECHANISM.

Patented Nov. 29, 1892..

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SELF ADJUSTING FEED MECHANISM.

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UNrTEn STATES PATENT OFFICE.

GUSTAVE EHRI-IARDT, OF PITTSBURG, PENNSYLVANIA.

SELF-ADJUSTING FEED MECHANISM.

SPECIFICATIQN forming part of Letters Patent No. 487,116, dated November 29, 1892. Application filed January 11, 1892. Serial No. 4:17, '7 (N mo l-l To aZZ whom it may concern:

Be .it known that I, GUsTAvE EHRHARDT, a citizen of the United States, residing at Pittsburg, county of Allegheny, and State of Pennsylvania, have invented a new and usefulImprovementin FeedMechanisms; and Idohereby declare that the following is a full, clear, and exact description of the invention, which will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, which form a part of this specification.

The object of my invention is to provide a self-adjusting feed mechanism for cold sawing, planing, and cutting machines, lathes, &c., whereby the speed is regulated and controlled by the resistance offered to the cutting-tool, thus avoiding all straining and twisting of the machinery.

Referring to the drawings, Figure 1 represents a plan view of asawing-machine of an ordinary and wellknown construction to which is applied my improved feed mechanism. Fig. 2 is a side view of the same. Fig. 3 is a plan view of the feed mechanism detached from the machine, and Fig. 4 is aside View of the same.

Referring to Fig. 1, in order to showthe application of my automatically-adjusting feed mechanism,A represents the main shaft of the sawing-machine, which derives power from the power-shaft B, which carries tight and loose pulleys O O and is connected to the main shaft by the gearing D. The sawcarriage E slides on the track-frame F and carries a gear G, which meshes with a pinion H, said pinion being carried by the carriage and being connected to the main shaft by a spline-and-groove connection 72, whereby the rotation of the main shaft is communicated through the pinion to the gear G, the shaft 9 of which is geared to the saw-arbor I. The feed-screw K is mounted at its ends in bearings k in the main frame of the machine and also extends through nuts e e on the carriage, whereby as the screw is rotated by power derived from the main shaft the carriage is advanced. The feed-screw is capable of a slight longitudinal movement in its bearings for the purpose of tightening or loosening a friction-clutch L, through which said power is derived. The clutch L consists of a disk or member M, which is rigidly secured to the extremity of the feed-screw and is provided with a conical rim m, which is adapted to fit in a conical recess in the side of the gear or positive member M, which is connected by gearing N to the main shaft. The smooth end of the feedscrew extends through the sleeve m, which forms the bearing for the gear orpositive member of the clutch, and is capable of sliding freely therethrough to cause the disk or variable member to engage or disengage the gear or positive member.

The gearing and reversing mechanism, which are indicated at N, form no part of this invention, and therefore it is not necessary to describe them in detail herein. It is sufficient to say that the movement of the main shaft is transmitted directly to the gear or positive member of the c utch, and the rotary motion thereof is imparted to the disk or variable member by frictional contact, the speed of the latter depending upon the firm ness of the contact, whichin turn is regulated by the position of the feed-screw. The normal position of the latter is such as to hold the members of the clutch in contact, so that the feed-screw rotates at the same rate of speed as the gear or positive member, and it is held in its normal position byatension device which is located at the opposite end of the feed-screw.

The tension device which I have shown in connection with my improved feed mechanism consists of a lever 0, provided with an adjustable weight P and connected by a series of levers and links to the adjacent end of the feed-screw, whereby the latter is normally held in the position shown clearly in Fig. 4 and also in Fig. 2. The lever O is provided with a handle Qand a short arm R, the length of which from the pivotal point r is very short compared with that arm of the lever 0 which carries the weight P, the free end of the arm R being pivotally connected to the lower and longer arm of an intermediate lever S, the upper and shorter arm of which is connected by means of a link T to the end of the feed-screw.

The parts of the mechanism being in the position indicated in Figs. u and 4:, with the clutch members firmly in contact and the feedscrew rotating at the same rate of speed as the gear or positive member M, the operation is as follows: When the saw-blade meets an obstruction or reaches a thicker section of the article which is being severed, the resistance to the advance of the saw is increased, thereby increasing proportionately the back-pressure upon the feed-screw, thereby causing the latter to yield slightly and decrease the frictional contact between the clutch members, the result of which is to reduce the speed of rotation of the feed-screw and cause the carriage to advance more slowly until the obstruction is passed. When the resistance to the saw becomes less, the tension device returns the feed-screw to its normal position, thereby again increasing the frictional contact between the members of the clutch and causing the feed-screw to rotate at its former rate of speed. If the obstruction is sufficient to prevent further advance of the saw, the back-pressure upon the feed-screw will completely separate the members of the clutch, so that the rotation of the feed-screw and the motion of the carriage will cease. Thus the speed of the saw-carriageavhich derives its motion from the main shaft of the machine, is antomatically adjustable, and is governed by the resistance or the varying resistances offered to the saw-blade, the amount of resistance which is necessary to repress the feed-screw being governed by the tension device, which may be adjusted to offer a greater or less opposition to the backward strain on the feed-screw by the arrangement of the adjustable weight toward or from the pivotal point of the lever 0. By placing said weight near the pivotal point of the lever less resistance is offered to the repression of the feed-screw, and aslighter resistance to the saw will reduce the speed of rotation thereof. By placing the weight near the extremity of .the lever the resistance to the repression of the feed-screw is increased, and a greater resistance to the saw is necessary to reduce the speed of rotation of said feed-screw.

The tension device which I have shown in the accompanying drawings is simple, compact, and efiective, and is, therefore, the form which I prefer to use in this connection; but I desire to have it understood that the details of arrangement may be altered to adapt it for use in various positions and under different conditions, and, having contemplated such changes and adaptations, I do not desire to be limited strictly to the precise construction shown and described. For instance, a powerfnl spring may be substituted for the weight, or may be inserted between the end of the framework of the machine and the collar U, which is shown in Fig. 4, the latter being objectionable from the fact that a spring does feed-screw, and the tension device to normally hold the members of the clutch in contact, substantially as specified.

3. In combination, the carriage carrying a cutting-tool, the main shaft, the feed-screw to operate the carriage and capable of longitudinal movement, the clutch having one of its members geared to the main shaft and its other member carried by the feed-screw, and the tension device connected to the feedscrew to normally hold the members of the clutch in contact, substantially as specified.

4. In combination, the carriage, the feedscrew capable of longitudinal movement, the clutch having a gear or positive member to receive the power and a variable or movable member carried by the feedscrew, and a tension device connected to the feed-screw, sub-' stantially as specified.

5. In combination, the carriage, the feedscrew capable of longitudinal movement, the friction-clutch having one of its members carried by the feed-screw, and the tension device having a weighted lever connected to the feed-screw, substantially as specified.

6. In combination, the carriage, the longitudinally-movable feed-screw, the frictionclutch having one of its members carried by the feed-screw, the tension device consisting of a lever having an adjustable weight and provided with a short arm, and an intermediate lever connected at one end to said short arm and at the other end to the feed-screw, substantially as specified.

7. Aself-adjusting feed mechanism having a longitudinally-movable feed-screw which is geared to the operating mechanism, a friction-clutch, one member of which is carried by said feed-screw, being interposed between the latter and said operating mechanism, substantially as specified.

In testimony whereof I affix my signature in presence of two witnesses.

GUSTAVE EHRHARDT. Witnesses:

HENRY C. LYON, JOHN GRAEBING, Jr. 

